1. (of ink or a pen) making marks that cannot be removed: "an indelible marker pen"
▪ not able to be forgotten:"the story made an indelible impression on me"
Word Originlate 15th century (as indeleble): from French, or from Latin indelebilis, from in- ‘not’ + delebilis (from delere ‘efface, delete’). The ending was altered under the influence of -ible.